JP3315964B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus capable of controlling an aperture in a lens direction or a short axis direction, and a vibrator for transmitting and receiving an ultrasonic wave to and from a subject in a long axis direction (scanning direction). The present invention relates to an ultrasonic diagnostic apparatus using probes arranged two-dimensionally in a short axis direction (lens direction).

[0002]

2. Description of the Related Art Conventionally, an ultrasonic diagnostic apparatus using a vibrator capable of controlling the aperture in the short axis direction is disclosed in Japanese Patent Application Laid-Open No. 9-526. FIG. 7 shows the configuration of a conventional ultrasonic diagnostic apparatus of this type. A transducer Pi, j has M rows in the short axis direction and N columns in the long axis direction (1 ≦ i ≦ M, in this case M
= 6, 1 ≦ j ≦ N, in this case N = 10). The short-axis aperture control circuit 210-j is connected to the vibrators in the j-th column. The configuration of the short-axis aperture control circuit 210-j in each column is the same. The short-axis aperture control circuit 210-10 corresponding to the vibrator in the tenth row has the preamplifier 200-k (k =
i, i = 4, k = 7-i), switch 201-k,
It comprises a diode 202-k and a protection circuit 203.
The short axis aperture control circuit 210-10 includes a transmitter 204-10 and a receiver.
205-10 is connected. A reception phasing circuit 206 is connected to outputs of the receivers 205-1 to 205-10. The switch 201-k is for controlling the aperture of reception. The switch 201-3 is turned on for an echo from a short distance, and the reception signal from the vibrator of i = 3, 4 is received by the receiver 205. Sent to -10. For this reason, the short-axis aperture for reception is narrow, and the resolution in the short-axis direction is high.
On the other hand, all switches for echoes from a long distance
202-k turns on, and the received signals from all the transducers Pi, 10 in the tenth row are sent to the receiver 205-10. For this reason, the reception aperture widens, the beam is strongly converged by the acoustic lens 220, and the resolution is high. The aperture changes in the same manner for the other rows. In this manner, a received signal with high resolution can be obtained from a short distance to a long distance.

[0003]

However, in the above conventional ultrasonic diagnostic apparatus, a large number of preamplifiers 200-200 are required.
It is necessary to dispose k and the switch 201-k near the arrayed transducers, which has a problem that the probe becomes large and heavy.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides an excellent ultra-light probe having a lightweight and easy-to-handle probe capable of controlling the aperture in the lens direction or the short axis direction without using a large number of preamplifiers and switches. An ultrasonic diagnostic apparatus is provided.

[0005]

In order to solve the above-mentioned problems, an ultrasonic diagnostic apparatus according to the present invention comprises an aperture formed by a plurality of vibrators arranged, and a high-frequency ultrasonic wave generated from each of the vibrators. the resistance adding means for the ratio of the frequency components are corrected and probe is greater than the transducer of the opening edge portion, the sensitivity difference between the respective transducers in the transducer opening the central portion, the
Subject received by the vibrator and passed through the resistance adding means
A receiving circuit that amplifies the echo signal from the, and band-limiting the echo signal , comprising a dynamic filter having high reception sensitivity of high-frequency components at short distances and high reception sensitivity of low-frequency components at long distances , The receiving circuit has a current input
It is an amplifier and a means to prevent reverse bias due to excessive input.
A grounded base circuit having a plurality of stages, wherein the current input
The input of the amplifier is connected to the transmission circuit that drives each of the transducers.
A narrow beam is obtained for high-frequency components that are often included in echoes from short distances, and a narrow beam is obtained for low-frequency components that are often included in echoes from long distances. A beam that is strongly converged by an acoustic lens or the like is obtained, and an ultrasonic diagnostic apparatus with high resolution from a short distance to a long distance can be realized. In particular, resistance addition
High precision cable for transmission and reception signals
Can be shared.

The ultrasonic diagnostic apparatus of the present invention is characterized in that the thickness of the transducer is smaller at the center of the opening of the probe than at the periphery of the opening. The center frequency of the vibrator is increased, and the ratio of the high frequency components of the generated ultrasonic waves can be increased.

Further, in the ultrasonic diagnostic apparatus of the present invention, the probe has an acoustic matching layer on the front surface of each of the transducers, and the center of the opening of the probe is closer than the edge of the opening. The thickness of the acoustic matching layer is small, and the center frequency of the vibrator is increased at the center of the opening, so that the ratio of high frequency components of generated ultrasonic waves can be increased.

Further, the ultrasonic diagnostic apparatus of the present invention includes a separating element connected to each of the transducers for correcting the transmission sensitivity of a low frequency, and the resistance adding means includes a receiving element for receiving the low frequency. The sensitivity is corrected, and the transmission / reception sensitivity of the low frequency component of the generated ultrasonic wave can be set to the same level at the center and the periphery of the opening.

[0009]

[0010]

In the ultrasonic diagnostic apparatus according to the present invention, each of the transducers is arranged in M rows and N columns, and with respect to the transducers in the same column, a high frequency component of an ultrasonic wave generated by the transducer at the center of the opening. Is large, the characteristics of the vibrators in the same row are the same, and the resistance adding means adds the outputs from the vibrators in the same column, and includes means for phasing the output obtained by the resistance addition. Therefore, the center frequency of the vibrator is increased at the central portion of the opening in the short-axis direction, and the ratio of the high frequency components of the generated ultrasonic waves can be increased.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a schematic block diagram of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. In FIG. 1, a probe 1 transmits and receives ultrasonic waves, and includes transducers P1 to P3 and addition resistors RS-1 to RS-3, and is arranged in a single row to form an aperture. are doing. The transmission circuit 2
The driving pulse is generated to drive the probe 1. Receiving circuit 3
Amplifies the signal received from the probe 1. The dynamic filter 4 is a bandpass filter whose center frequency is variable according to the depth of arrival of the echo signal reflected from the subject. The display unit 5 displays an output from the dynamic filter 4 as an image.

FIG. 2A is a diagram showing the frequency characteristics of the sensitivities of the oscillators P1 to P3 before correction, FIG. 2B is a diagram showing the frequency characteristics of the sensitivities of the oscillators P1 to P3 after correction, and FIG. Indicates the frequency characteristic of the gain of the dynamic filter 4.

The operation of the ultrasonic diagnostic apparatus configured as described above will be described with reference to FIG. First, the transmission circuit 2 generates a broadband and large-amplitude drive pulse.
The drive pulse is applied to the transducers P1 to P1 through the addition resistors RS-1 to RS-3.
Driving P3 generates an ultrasonic pulse. In this embodiment, the frequency characteristics of the oscillators P1 to P3 are such that, as shown in FIG. 2A, the oscillator P2 at the center of the opening has a high center frequency and high transmission sensitivity up to a high frequency range. Vibrator P1 at the edge,
P3 has a low center frequency and low transmission sensitivity at high frequencies. On the other hand, the vibrators P1 and P3 have high transmission sensitivity at low frequency, while the vibrator P2 has low transmission sensitivity at low frequency. The addition resistors RS-1 to RS-3 are connected to the vibrators P1 and P3 and the vibrator.
The transmission and reception sensitivity difference of P2 is corrected. The sensitivity of the transducers P1 and P3 in the low frequency range is reduced and corrected by using a series resistor, as shown in FIG. 2 (b). Can be at the same level as

The ultrasonic pulse generated in this manner is
The light is reflected by the subject and received by the transducers P1 to P3 as an echo signal. The received signals are added by the addition resistors RS-1 to RS-3. Regarding the reception sensitivity, the addition resistors RS-1 to RS
With -3, it can be corrected similarly to the transmission sensitivity. The reception signals passing through the addition resistors RS-1 to RS-3 are amplified by the reception circuit 3 and are filtered by the dynamic filter 4.

FIG. 2C shows the dependence of the frequency characteristic of the dynamic filter 4 on the distance to the reflector. As shown in FIG. 2 (c), the dynamic filter 4 passes high frequency components for echoes from a short distance, and passes low frequency components for echoes from a long distance. Therefore, at short distances, the sensitivity for transmission and reception by the transducer P2 is high. That is, the sensitivity is high at the center of the opening of the probe 1. Further, at long distances, the sensitivity is high for transmission and reception by the transducers P1 to P3. That is, the sensitivity is high over the entire opening of the probe 1. The echo signal that has passed through the dynamic filter 4 in this way provides a narrow beam with a narrow aperture for short distances, a beam with a wide aperture and high directivity for long distances, or an acoustic lens or the like. Strong convergence is possible and a narrow beam is obtained.

As described above, according to the first embodiment,
Using a vibrator P2 with a high center frequency at the center of the opening and vibrators P1 and P3 with a low center frequency at the periphery of the opening, and using an addition resistor RS so that the sensitivity is the same level at low frequencies.
-1 to RS-3, the dynamic filter 4 has high reception sensitivity for high-frequency components at short distances and high reception sensitivity for low-frequency components at long distances. High resolution can be obtained.

(Embodiment 2) FIG. 3 shows a schematic block diagram of a transmitting / receiving section of an ultrasonic diagnostic apparatus according to Embodiment 2 of the present invention. In FIG. 3, a probe 11 transmits and receives ultrasonic waves, and has an aperture formed by arranging a plurality of transducers P10 to P15. The acoustic matching layer 15 includes the vibrator P10
P15 to improve the electro-acoustic conversion efficiency, and are made of, for example, a resin material. The acoustic lens 16 focuses the ultrasonic beam, and is made of, for example, resin. The drive pulse generated by the transmission circuit 12 is applied to the separation elements ID-10 to ID-12 via the transmission / reception cable 17. Each of the separation elements ID-10 to ID-12 includes a resistor, a diode, and the like as shown in the equivalent circuit of FIG. For example, the separating element ID-10 includes a series resistor RI-10, diodes DI-10,1 and DI-1.
It consists of 0,2. The summing resistors RS-10 to RS-12 are connected to the oscillator P
It adds the received signals from 10 to P15. Received signals that have passed through the addition resistors RS-10 to RS-12
The signal passes through 17 and is amplified by the receiving circuit 13. The output of the receiving circuit 13 is connected to a dynamic filter 14.

The vibrators P10 to P15 are constituted by piezoelectric vibrators,
The transducers P12 and P13 at the center of the opening of the probe 11 have a thin piezoelectric body and a high center frequency. The acoustic matching layer 15 has an effect as a quarter-wave plate, and the thickness of the matching layer 15 is selected so as to be equivalent to a quarter of the wavelength at the resonance frequency of the vibrator.
Since the resonance frequencies of the oscillators P12 and P13 at the center of the opening are high,
The acoustic matching layer 15 becomes thinner at the center of the opening. In this way, the center frequency of the vibrator P12 and the vibrator P13 at the center of the opening can be increased, and the sensitivity can be increased at high frequencies. Further, the center frequency of the vibrators P10 and P15 at the periphery of the opening can be lowered, and the sensitivity can be lowered at high frequencies. Further, the difference in sensitivity between the transducers P10 to P15 at low frequencies is determined by the separation elements ID-10 to ID-12 shown in FIG.
Can be corrected by the resistance values of the additional resistors RI-10 to RI-12 shown in FIG. The addition resistors RI-10 to RI-12 are connected to the receiving circuit 13.

The operation of the ultrasonic diagnostic apparatus configured as described above will be described with reference to FIG. First, the transmission circuit 12 generates a drive pulse having a positive polarity of about several tens of volts or more. The drive pulse is applied to the separation elements ID-10 to ID-12. In FIG. 4, the drive pulse passes through the separation elements ID-10 to ID-12 because it is larger than the forward voltage of the diode. Series resistance of separation elements ID-10 to ID-12 RI-10 to RI-12
Is used to make the transmission sensitivities of the transducers P10 to P15 in the low frequency range the same. Note that the vibrators P10 to P
Since the received signal from 15 is smaller than the forward voltage of the diode, it does not pass through the separation elements ID-10 to ID-12. Separation element
ID-10 is connected to transducers P10 and P15. Similarly, ID-11
Is connected to P11 and P14, and ID-12 is connected to P12 and P13, and the drive pulse is applied symmetrically to the arranged transducers P10 to P15 around P12 and P13. In order to efficiently apply the driving pulse, the values of the resistors RI-10 to RI-12 of the separation element are selected to be low, so that the addition resistors RS-10 to RS- shown in FIG.
The percentage of drive pulses passing through 12 is low.

FIG. 5 shows an equivalent circuit of the receiving circuit 13, which is configured as a grounded base type current input amplifier having means for preventing reverse bias due to excessive input. In FIG. 5, the emitter of the NPN transistor Tr1 of the receiving circuit 13 is an input, and additional resistors RS-10 to RS-12 are connected.
Connected to power supply VE via R1. The base of Tr1 is connected to a power supply line via a capacitor C1. The collector of TR1 is an output and is connected to a power supply line via a resistor R2. In this way, the transistor TR1 forms a grounded base circuit, so that the input impedance can be extremely low. Also, the gain of this circuit is
Determined by the ratio of -10 to RS-12 and resistance R2, oscillators P10 to P15
Is accurately corrected. The transmission circuit 12 is connected to the emitter of the transistor TR1, and a positive high-voltage pulse is applied. In this case, the potential of the emitter becomes higher than that of the base and the collector, but no excessive reverse bias is applied by turning on the diodes D1 and D2. When the diode D1 turns on, the voltage of the power supply line also increases.
D4 is turned off, and the drive pulse is not absorbed by the power supply VC. Further, since the resistances R1, R3, and R4 can be set to sufficiently high values, the influence on the drive pulse due to the turning on of the diodes D1 and D2 is extremely small. When the drive pulse swings to the negative polarity, the power supply VC and the transmission circuit 12 are electrically connected. However, by providing the power supply VC with a current limiting function, the drive pulse can be prevented from being absorbed by the power supply VC.

As described above, according to the second embodiment,
By reducing the thicknesses of the piezoelectric vibrators P12 and P13 and the acoustic matching layer 15 at the center of the opening of the probe 11, the reception sensitivity of high-frequency components can be increased at the center of the opening. Also, the transmission sensitivity can be corrected using the separation elements ID-10 to ID-12 so that the transmission sensitivity is at the same level at the low frequency, and the reception sensitivity is the same at the low frequency. By using the addition resistors RS-10 to RS-12 and the current input amplifier of the reception circuit 13, the reception sensitivity can be corrected with high accuracy. Also, the current input amplifier constituting the receiving circuit 13
By providing a diode that prevents reverse bias due to excessive input, the influence on the drive pulse can be reduced. By using the dynamic filter 14 having high reception sensitivity for high-frequency components at short distances and high reception sensitivity for low-frequency components at long distances, high resolution can be obtained from short distances to long distances.

In the above description, an example has been described in which both the piezoelectric vibrator and the acoustic matching layer are thinned to increase the center frequency. However, even if only one of them is thinned, the center frequency can be increased. it can. FIG. 3 shows an example in which the thickness of the piezoelectric vibrator changes continuously, but the thickness may be changed stepwise.

(Embodiment 3) FIG. 6 is a schematic block diagram of an ultrasonic diagnostic apparatus having two-dimensionally arranged transducers according to Embodiment 3 of the present invention. In FIG. 6, a probe 21 transmits and receives ultrasonic waves, and transducers Pi, j (1) arranged in M rows in the short axis direction and N columns in the long axis direction.
.Ltoreq.i.ltoreq.M, in this case M = 6, 1.ltoreq.j.ltoreq.N), and an acoustic lens 27 arranged on the front surface thereof. The transmission circuit 22-j corresponding to the j-th row of transducers Pi, j arranged in the short axis direction includes a separation element ID-k, j (k = i, i when i ≦ 3).
If ≧ 4, k = M + 1-i), and the receiving circuit 23-j is connected to the addition resistor RS-k, j. The outputs of the N receiving circuits 23-j are
The signal is delay-combined by the reception phasing circuit 26. The output of the reception phasing circuit 26 is processed by the dynamic filter 24 and displayed on the display unit 25.

The operation of the ultrasonic diagnostic apparatus configured as described above will be described with reference to FIG. First, j
Among the vibrators P1, j to P6, j in the row, the central frequencies of the vibrators P3, j and P4, j at the center of the opening are high in the short axis direction,
High sensitivity at high frequencies. At a low frequency, the vibrator is formed by the separation element ID-k, j and the addition resistor RS-k, j.
The sensitivity is corrected so that the sensitivities of P1, j to P6, j are at the same level. Therefore, at a short distance, the sensitivity is high at the center of the opening of the probe 21 in the short axis direction. At a long distance, transmission and reception are performed using the entire opening of the probe 21. The reception signal thus obtained is input to the reception phasing circuit 26 via the reception circuit 23-j, and the beam is formed in the long axis direction. The output of the reception phasing circuit 26 is processed by the dynamic filter 24. Since the output of the dynamic filter 24 has many high frequency components at a short distance, the aperture is narrowed in the short axis direction, and the beam width is narrow. Further, since there are many low-frequency components at a long distance, the aperture is wide in the short axis direction, and strong convergence is possible by the action of the acoustic lens 27 and the like.

[0026]

As described above, according to the present invention, an aperture is constituted by a plurality of transducers arranged, and the ratio of the high frequency components of the ultrasonic waves generated from the transducers is determined by the transducer at the center of the aperture. A probe that is larger than the transducer at the periphery of the opening, a resistance adding means for correcting a sensitivity difference between the respective transducers , and a signal received by the transducer and passing through the resistance adding means.
Receiving circuit that amplifies the echo signal from the subject
The serial echo signal band-limited, the short-range high reception sensitivity of the high frequency component, and a high dynamic filter receiving sensitivity of the low frequency components in the long distance, the receiving circuit
Is a current input amplifier, and reverse bias due to excessive input
Comprising a grounded base circuit having means for preventing
A transmission circuit in which the input of the current input amplifier drives each of the vibrators.
Because it is connected to the road , aperture control is substantially possible,
An excellent ultrasonic diagnostic apparatus having a lightweight and easy-to-handle probe can be obtained.

[0027]

As described above, according to the present invention, an aperture is constituted by a plurality of transducers arranged, and the ratio of the high frequency components of the ultrasonic waves generated from the transducers is determined by the transducer at the center of the aperture. A large probe, a resistance adding means for correcting the sensitivity difference between the transducers, and band-limiting the echo signal received from the subject, the reception sensitivity of high-frequency components is high at short distances And a dynamic filter having high sensitivity for receiving low-frequency components at long distances, so that it is possible to obtain an excellent ultrasonic diagnostic apparatus having a lightweight and easy-to-handle probe capable of substantially controlling the aperture. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention.

FIG. 2A is a diagram illustrating a frequency characteristic of the ultrasonic oscillator according to the first embodiment of the present invention; FIG. 2B is a diagram illustrating a corrected frequency characteristic of the ultrasonic oscillator according to the first embodiment of the present invention; Of Dynamic Characteristics of Dynamic Filter in First Embodiment

FIG. 3 is a block diagram of an ultrasonic diagnostic apparatus according to Embodiment 2 of the present invention.

FIG. 4 is an equivalent circuit diagram of a separation element according to a second embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of a receiving circuit according to a second embodiment of the present invention.

FIG. 6 is a schematic block diagram of an ultrasonic diagnostic apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a schematic block diagram of a conventional ultrasonic diagnostic apparatus.

[Explanation of symbols]

 Reference Signs List 1 probe 2 transmission circuit 3 reception circuit 4 dynamic filter 5 display unit 11 probe 12 transmission circuit 13 reception circuit 14 dynamic filter 15 acoustic matching layer 16 acoustic lens 17 transmission / reception cable 21 probe 22 transmission circuit 23 reception circuit 24 Dynamic filter 25 Display unit 26 Reception phasing circuit 27 Acoustic lens

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-144699 (JP, A) JP-A-57-203434 (JP, A) JP-A-58-29455 (JP, A) 158142 (JP, A) JP-A-7-22870 (JP, A) US Patent 5840032 (US, A) WO 91/13588 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) A61B 8/00

Claims (5)

(57) [Claims] An aperture is constituted by a plurality of transducers arranged, and a ratio of a high-frequency component of an ultrasonic wave generated from each of the transducers is higher than that of a transducer at the periphery of the opening in the transducer at the center of the opening. And a resistance adding means for correcting a sensitivity difference between the respective transducers , and a signal received by the transducer.
And the echo signal from the subject passing through the resistance adding means.
A receiving circuit for amplifying the items, said echo signal band-limited, the short-range high reception sensitivity of the high frequency component, the long distance and a receiving sensitivity of the low frequency components is high dynamic filter, the reception circuit Is a current input amplifier
And means to prevent reverse bias due to excessive input
The input of the current input amplifier is constituted by a grounded base circuit.
Is connected to a transmission circuit that drives each of the transducers . 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the thickness of the transducer is smaller at the center of the opening of the probe than at the periphery of the opening. 3. The probe has an acoustic matching layer on the front surface of each of the transducers, and the thickness of the acoustic matching layer is smaller at the center of the opening of the probe than at the periphery of the opening. The ultrasonic diagnostic apparatus according to claim 1 or 2, wherein: 4. A separating device connected to each of the transducers for correcting transmission sensitivity at a low frequency, wherein the resistance adding means corrects reception sensitivity at a low frequency. The ultrasonic diagnostic apparatus according to claim 1. 5. The transducers are arranged in M rows and N columns, and the ratio of the high frequency components of the ultrasonic waves generated by the transducers at the center of the opening is large with respect to the transducers in the same column. a characteristic of the vibrator same, the resistance adding means adds the output from the oscillator in the same column, any one of claims 1 to 4 including means for phasing relative to the resistance summed output An ultrasonic diagnostic apparatus according to item 1.